PRO ChopDate,YYMMDD,YY,MM,DD,Error=error

tmp=Round(yymmdd+0.D0)	; convert to numeric type if possible

IF tmp LT 710000L THEN BEGIN
    Message,'Date is too early',/Informational
    yy=-1 & mm=-1 & dd=-1 & error=1
    Return
    ENDIF

IF 991231L LT tmp THEN BEGIN
    Message,'Date is too late',/Informational
    yy=-1 & mm=-1 & dd=-1 & error=1
    Return
    ENDIF

dd=tmp MOD 100
tmp=tmp/100
mm=tmp MOD 100
yy=(tmp/100)+1900
error=0

Return
END